The present invention relates to a sliding vehicle door, and more particularly to a power operated drive system therefore.
In various types of vehicles, it is known to provide a sliding door where the door moves along a fixed path generally parallel to a side wall of the vehicle. Typically, the sliding door moves generally into the plane of the door opening during a portion of its respective final closing and initial opening movements. Movement into the plane of the door opening allows the sliding door to be flush with the side wall when fully closed. Movement out of the plane of the door opening during its initial opening movement allows the sliding door to be along side of, and parallel to, the side wall of the vehicle.
Guide rails or tracks are commonly attached to the top and bottom portions of the door opening to guide the sliding door. Typically, end portions of the various guide rails are curved inwardly with respect to the vehicle body to provide the out of plane movement. Roller assemblies are fastened to the respective upper and lower forward ends of the sliding door for movement along the guide rails to guide the door through its opening and closing movements.
Movement of the sliding door generally parallel to the side wall of the vehicle requires high displacement with low force to achieve the transitional movement since only frictional resistance and gravity resistances due to changes in grade must be overcome. Movement of the sliding door through the curved guide rail track requires low displacement with high force. As an elastomeric weather seal surrounding the door opening must be overcome and an unlatched striker must be engaged to lock the sliding door.
During manual operation, sliding van doors are typically moved with great momentum through the entire closing movement in order to ensure full weather strip compression and latch operation at the end of such movement. Powered operation, however, is relatively more complicated. To achieve effective operation, the drive system must drive the sliding door along the track in a reasonable time and provide enough force to overcome the elastomeric weather seal and the unlatched striker to assure proper closing of the sliding door. The drive system must also drive the sliding door through the change in direction of the curved guide rail. Although numerous effective powered drive systems are currently available, each is rather complicated and expensive to manufacture.
Accordingly, it is desirable to provide a powered drive system for a vehicle sliding door which is uncomplicated and cost effective.